(1) Field of the Invention
The invention relates to a portable electronic device having a protective foldable cover with a built-in membrane keyboard, and more particularly to the portable electronic device who presents the membrane keyboard at a stand state thereof supported by the protective foldable cover.
(2) Description of the Prior Art
In the art, application of the keyboard, in particular the QWERTY keyboard, can be widely seen in most of the electronic devices. Also, for versatile input methods in this field, the keyboard input is always the most feasible and comfortable means for users of any kind of electronic devices. It is obvious that the application of keyboards can have no problem to the table-top or larger-sized electronic devices, but yet problems arise while the electronic device is miniaturized into a potable size. Apparently, space for accommodating a solid keyboard is merely found for those portable electronic devices, such as cellular phones, flat or tablet PCs, PDAs and so on.
Now, various efforts have been made to provide a keyboard as the main or auxiliary input means for the portable electronic devices. One of those efforts can be seen in the RIM Blackberry. As shown in FIG. 1, a schematic view of a typical Blackberry 1 is illustrated. The Blackberry 1 has a miniaturized, but in a full scale. QWERTY keyboard 2 located lower to the screen 3 thereof. Though the built-in keyboard 2 makes easy for input to be shown on the screen 3, yet the size of the Blackberry 1 has made cumbersome to the finger input to the keyboard 2, and also a limited screen size can only be provided to the Blackberry 1.
Another effort is shown in FIG. 2, in which a full-scaled removable mechanical keyboard 2a as an auxiliary input means is provided in a plug-in form to the portable electronic device 1a. Such a design can be seem in the Samsung Galaxy series and ASUS Transformer Tabs. In this application, though the room on the electronic device for constructing the screen is freed, yet a separate full-scaled keyboard 2a make a tablet or flat PC no difference to a traditional notebook PC. Besides of the higher cost and the increased volume, such a kind of this application has been trading off merits of the tablet PC 2a. 
The aforesaid two efforts are devoted to building hardware keyboards to the electronic devices, while the following efforts work on to provide imaged software keyboards.
A further effort is schematically shown in FIG. 3, where a tablet PC 1b with dual screens 3bu and 3bl is illustrated, and in which the touch screen 3bl can be transformed, as required, into an imaged keyboard for inputting to the upper screen 3bu. Such a design can be seen in tablet PCs of Sony, Acer and ICONIA. In this application, though the imaged screen presentable to the lower screen 3bl can provide a keyboard application close to a membrane keyboard, yet it also sacrifices half of displayable screens of the PC to mimic an imaged keyboard. Cost and volume needed to provide such a service make meaningless to the appearance of the dual-screen tablet PC 1b. 
Also, a further effort in software keyboard is usually seen to most of high-level mobile phones and tablet PCs. Referred to FIG. 4, the electronic device 1c can provide portion 3c′ of the touch screen 3c (the lower part as shown) to be shaded and become a temporary imaged keyboard per an input request. In this application, the imaged keyboard can only be small-sized keyboard which is unfriendly to a finger control, and also part of the displayable screen is sacrificed.
Definitely, more efforts are needed to provide a convenient and friendly keyboard structure for the current portable electronic devices. This present invention is one of this devotion.